I bought beat saber the day I got my Quest 2 in the VR store within the headset. The game works fine, although now that I have it linked to my PC the game will not show in my oculus library on the PC app. I am logged into the same and only Oculus account I have, I have checked the boxes in the filters to allow it to show uninstalled games and games from unknown sources, which did enable it to show my other VR games I have installed on steam but not beat saber. I can view the game in the store and it does not say I own the game and wants me to buy it again. The reason it needs to be in the library is so it creates an install folder on my pc so I can load custom songs, but I really dont want to have to buy the game twice because that really doesnt seem fair.
So I believe the answer is that the PC app only supports the Oculus Rift store, and I bought it on the Quest store. Im absolutely furious right now, if I were to have bought the game on either of those, I'd be able to modify the game; while if I hadnt bought it on the quest, I wouldnt be able to play without virtual desktop/link. This is clear exploitation, Im contacting my bank in attempt to void the first purchase of the game to actually make things right. If im wrong then my apologies, but in that case maybe there should have been a way for me to contact you guys and actually get a **bleep** answer/solution.
I can understand your frustration and you are correct, I don't think Beat Sabre is a cross buy app. It's up to the game developer to determine what is and is not cross buy. Their reasoning is some games require a lot of work to get them to play on the Quest. There are games that are cross buy info Here